A Study of Neutron Production by Cosmic Muons in Liquid Scintillator

The Daya Bay Reactor Neutrino Experiment is designed to measure the neutrino mixing angle, θ_13, with a sensitivity of sin^2(2θ_13) < 0.01 at 90% confidence level. Neutrons produced by cosmic muon spallation constitute one of the main backgrounds, and an understanding of the neutron yield of a muon is important. Since Daya Bay has a very good muon tracking system, muon tracks can be reconstructed accurately. The neutron yield can be determined by constructing a fiducial volume around each muon track. The neutron yield is found to be of the order of 10^−4 cm^2 /µ/g for each experimental hall of Daya Bay. The results show a gradual dependence on muon energy, and are in agreement with other measurements. Since Daya Bay is capable of measuring energy deposition, the neutron events show enhanced energy deposition.